b'2.1 FUEL FABRICATION AND PROPERTIESThermal Properties of ATF CladdingsPrincipal Investigator: Tsvetoslav R. Pavlov Team Members/Collaborators: Lorenzo J. Vega Montoto, Michael C. MarshallThe new methodsT hermal expansion and totalAccomplishments:hemispherical emissivityThe current work could be summa-values are critical to enablerized by the following goals:demonstrated forlicensing of new nuclear fuel and thermal expansioncladding materials. Thermal expan- 1.Develop and establish methods and total emissivitysion is critical for establishing thefor the measurement of:characterization of ATFdimensional changes of the clad- a.thermal expansion of tubular cladding materials isding during irradiation while totalcladding geometries in the critical for supportingemissivity dictates the radiative heatradial and axial measure-the qualification of ATFtransfer at the external and internalment directions from room cladding materials cladding surfaces which influencestemperature to 1200C.the temperature profile across theb.total emissivity from room fuel and the cladding. Both proper- temperature to 1200C.ties are critical for fuel performance codes to predict the thermo-mechan- 2.Deploy new methods/tech-ical behavior of novel fuel andniques for the characterization cladding materials and to maintainof ATF cladding specimen.necessary safety margins duringThermal expansion of tubular reactor operation. samples was measured using a Project Description: Netzsch push-rod dilatometer. A Capabilities at Idaho National Labo- schematic of the equipment used ratory were further developed tois shown in Figure 1a and pictures enable the measurement of thermalof the post-test material (stain-expansion (using push-rod dilatom- less steel type 316) are shown in etry) and total emissivity (usingFigure 1b. Stainless steel 316 tubes Laser Flash Analysis (LFA) andwere used as surrogate cladding Fourier Transform Infrared (FTIR)materials (instead of Zircaloy Spectroscopy). For the first time,tubes). An example data set used a new data analysis package wasto validate the methodology is developed to enable the evaluationshown in Figure 2. The modified of total emissivity from laser flashthermal expansion method was data. Measurements were performedsubsequently applied to various ATF between room temperature andcladding tubes manufactured using 1200C and the new methodologiesdifferent fabrication parameters. were validated using availableTemperature dependent thermal reference materials. Finally, theexpansion results were collected methodologies were applied to ain the axial and radial directions.range of accident tolerant fuel (ATF)A laser flash setup (see Figure 3a) cladding materials. was used to determine the total emissivity as a function of tempera-32 2023|AFC ACCOMPLISHMENTS'